SEM 



652 



SEM 



concentrated bv evaooration till its tem- 

 perature reaches 536, but if the process 

 be carried further, oxygen pas is evolved, 

 and the acid is changed to the selenious. 

 It forms seleniaten with salitiable bases. 



SELE'NIET. A compound formed by the 

 union of selenium with a metallic base. 

 The best known is selenietted hydrogen, a 

 gaseous compound, which bears a strong 

 analogy to sulphuretted hydrogen, but it 

 acts with greater energy. 



SELE'NIOUS ACID. A volatile and crys- 

 tallisable acid, formed by burning sele- 

 nium in oxygen gas, or by heating it in 

 nitric or nitro-muriatic acid. It was for- 

 merly called selenic acid. 



SELE'NIO-CYAN'OGEN. A compound of 

 selenium and cyanogen, discovered by 

 Ker/elius. It has not yet been obtained 

 in a separate state. 



SEI/EXITE, Gr. ff&wrr,;. 1. A sub- 

 species of sulphate of lime of two varie^ 

 ties, massive and acicular. 2. A com- 

 pound of selenious acid with a base. 



SELE'NIUM, from tnXr,v/i, the moon. A 

 metalloid principle, obtained by Berze- 

 lius from the pyrites of Fahlun, and which 

 from its chemical properties he places be- 

 tween sulphur and tellurium. It has, 

 however, more properties in common 

 with the former than with the latter sub- 

 stance. Selenium, after being fused and 

 slowly cooled, is of a blueish-grey colour, 

 with a glistening surface, but it is of a red- 

 dish-brown when quickly cooled, and has 

 a distinct metallic lustre. It is brittle, 

 but not hard, and has a tendency to as- 

 sume a crystalline form. Sp. gr. 4'3 , 

 melting point, 225 F., but assumes a 

 pasty consistency at 212. 



SELEU'CID^E. In chronology, the Syro- 

 Macedonian era: a computation of time 

 commencing from the establishment of 

 the Seleucidae, a race of Grecian kings, 

 which reigned in Syria as successors of 

 Alexander the Great ; the Jewish rab- 

 bins call it the era of contracts, and the 

 Arabs the era of two horns. It began 

 B.C. 310? 



SELT-ACT'ING. A term applied to se- 

 veral automatic contrivances for super- 

 seding the manual labour which was pre- 

 viously necessary to manage a machine 

 of the same nature. 



SELT'ZER WATER. A mineral water of 

 Keider Seltzer, a place in Germany, about 

 ten miles from Frankfort-on-the-Maine. 

 It contains muriate of soda, carbonates of 

 magnesia, soda, lime, and a large quantity 

 of free carbonic acid. 



SEI/VAGE, ) Dutch, zelf-kant, self-bor- 



SEL'VEDGE. } der. In manufactures, the 

 edge of cloth where it is closed by com- 

 plicating the threads. 



SE'MAFHORE, ffr,ua,, sign, and $'.%&, 

 I bear. A telegraph. 



SEME' (Fr.), sown. In heraldry, strewed 

 with figures., as stars and the like. 



SEMECAB'PI:S. The Marking-nut tree. 

 A genus. Fentaiidria Trigynia. Xam 

 from trifAiuu, to mark, and x^o;,a. 

 fruit, on account of the use that is made 

 of its nut in the East Indies, to mark 

 table-linen and articles of apparel. The 

 S. anacardium was supposed to be the tree 

 which affords the Malacca bean ; which, 

 however, is the produce of the Anacar- 

 dium Indicum. 



SEMEIOT'ICS, from ryu-uvt, a sign. That 

 part of medicine which considers the 

 signs of disease. It comprehends diagnosis 

 and prognosis. 



SE'MEN ADJOW'AEN. Ad.jowan seed. 

 A seed, the produce of the Ammicopticum, 

 imported from India. It is used in me- 

 dicine for its exciting and carminative 

 virtues. 



SEM'I. A Latin prefix signifying half. 

 It answers to the Greek hemi, and French. 

 demi. 



SEM'I-ARIANS. In church history, a branch 

 of Arians who, in appearance, condemned 

 the errors of Arius, but acquiesced in some 

 of his principles, disguising them under 

 milder terms. Thus, they admit the Son, 

 to be like the Father by a peculiar pri- 

 vilege. 



SEM'IBREVE, from semi and breve. In 

 music, a note of half the duration or time 

 of the breve. It is equal to two minims, 

 or four crotchets, or eight quavers. 



SEM'ICOLON, from semi and colon. In 

 grammar, a point marked thus (;), de- 

 noting a pause in reading greater than 

 the comma, and of less duration than the 

 colon, and of half the duration of the 



In analysis, 

 a curve of the second order, defined by the 

 equation y* = ax'. It is the evolute of 

 the common parabola. 



SEM I-DIAPA'SON, from semi and diapason. 

 In music, an imperfect octave. 



SEMI-DIAPEX'TE, from semi and diapente. 

 In music, an imperfect fifth. 



SEMI-DIATE>'SARON, from semi and dia- 

 tessaron. In music, an imperfect fourth. 



SEMI-DI'TOJJE, from semi, for hemi, and 

 ditone. In music, a lesser third, having 

 its terms as 6 to 5. 



SEMI-FLOS'CCLOSE, Lat. semiflosculo&us. 

 In botany, a compound flower is so desig- 

 nated, when its florets have the limb of 

 the corolla produced in a ligulate shape 

 on the outer side only. The dandelion 

 and hawkweed are examples. 



SEMI-MET'AL. An old name for such 

 metals as a re not malleable ; e.g. bismuth, 

 arsenic, nickel, antimony, zinc, cobalt, 

 manganese, tungsten, molybdenum, ura- 

 nium, &c. 



SEMIMIN'IMA. In music, a 

 or crotchet. 



